package com.rr.learningdemo.structure;

import java.util.HashMap;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @author RR
 * @date 2021/3/13 14:13
 */
public class HashMapDemo {
    public static void main(String[] args) throws InterruptedException {

        HashMap<String, String> map = new HashMap<>();
        ConcurrentHashMap<String, String> concurrentHashMap = new ConcurrentHashMap<>();

        map.put(null, "1");
        map.put("1", null);
    }
}
